Ultra hush exhaust system (uhes)

ABSTRACT

An exhaust noise attenuation system mounted to a Jet Engine exit turbine frame for noise attenuation with an ULTRA THRUST REVERSER System mounted at the exhaust end, aft end of the exhaust noise attenuation system, to provide deceleration after landing of the aircraft. The exhaust noise attenuation system consists of double walled duct which can be either of constant circular, square or elliptic cross section or convergent section with variable cross-section area, made of sheet metal double walls with a perforated inner wall or skin except in the areas where there are solid non-perforated corrugations or hat sections which act as frames for structural integrity of the double walled duct, and a non-perforated outer wall or skin, with an appropriate noise attenuation material, assuming honeycomb for the sake of discussion since it is widely used, sandwiched between the inner perforated and outer solid skins of the duct. The sound attenuation material is placed in between the corrugations/hat sections over the perforations of the inner skin. The double walled duct is connected to a nozzle/ring bolted to the engine frame using two or more struts. In the shown figures the inventor used four (4) struts for depiction. Hinged inlet Doors are mounted at the forward end of the double skin duct, controlled by the pilot or the engine control system, to control the flow of ambient air sucked into the exhaust system by the eductor action, to optimize the engine performance, noise signature and reduce ram drag during flight. The doors can also be closed tight during flight to reduce ram drag and to create a smooth surface for the ambient air flowing over the surface of the exhaust system. However, the doors can be fitted with smaller doors or scoops to provide a limited amount of airflow to cool off the walls of the inner perforated duct. A movable exit cone can be used with the convergent duct configuration to optimize the exit area of the double walled duct to optimize the engine performance. An ULTRA THRUST REVERSER SYSTEM is mounted at the aft end of the double walled duct, consists of two improved design clamshell doors mounted on either side of the top and bottom of the double walled duct, fitted with two unique design actuators mounted one on each side of the external sides of the duct between the clamshell doors and the duct, possibly in a depression in the duct called blister, assuming them to be hydraulic actuators for discussion purposes. The actuators drive the clamshell doors using linkages pivoted to the exterior of the double walled duct, connecting the doors to the actuators, to deploy the doors aft of the double walled duct during deceleration after landing, diverting the exhaust gases forward to slow down the aircraft, but also drive the two movable fairings during thrust reverser operation to enclose the reversed exhaust flow forward to prevent its impingement on the skin of the aircraft.

FIELD OF INVENTION

This invention relates to what is known in the Aviation Industry as ahush system aiming at reducing the noise signature of older types of jetengines known as Turbojets or Low Bypass Jet Engines.

This patent relates to the Application Document No. 61/626,873 Filed onOct. 5, 2011.

BACKGROUND OF THE INVENTION

An ejector/eductor (those two words are used interchangeably)arrangement using a double walled duct mounted to the aft engine frameand method of reducing jet engine noise are disclosed wherein theprimary combustion gas stream of the jet engine is ejected into a mixingsection or zone of the double walled duct, into which a secondaryexternal cool gas stream from ambient air is injected at a velocitysufficient to create a mixed flow condition, resulting in rapid mixingof the primary and secondary gas streams both in the mixing zone. Theejector, in the convergent configuration, can be provided with means foradjusting the exit area of the mixing section or zone to match theengine operating conditions so as to create proper conditions within themixing zone for noise suppression. Noise suppression by the method andmeans disclosed occurs at all frequencies with probably a minimal lossof thrust, and possibly a slight gain in thrust due to mass flowincrease from the inducted ambient air which can increase the overallmomentum of the exhaust gases.

The ULTRA HUSH EXHAUST SYSTEM (UHES) is an ejector/eductor hush kit forolder types of Airliners and General Aviation Business lets powered bywhat is referred to as Low By-pass jet engines or Turbojet engines whichgenerate a very loud acoustic signature. This high acoustic signatureresults in noise pollution at airports and undesirable noise duringApproach, Take-Off or flying at low altitude over residential areaslocated near the approach path of airports. THE ULTRA HUSH EXHAUSTSYSTEM is invented to retrofit the current exhaust system of theseaircrafts with THE ULTRA HUSH EXHAUST SYSTEM (UHES) to comply withstrict airworthiness noise regulations which are not met by these typesof aircrafts, thereby extending their service life.

The UHES ejector hush exhaust system adapts THE ULTRA and/or SQUARETHRUST REVERSER SYSTEM, U.S. Pat. Nos. 5,615,834 and 7,043,897, withimprovements to the clamshell doors, and the actuation system. TheReverser/Eductor system decelerates the aircraft after landing andreduces the jet engine noise to acceptable noise levels during Take-offand Approach for landing to meet stricter airworthiness noiseregulations. This in turn will extend the service life of this type ofaircrafts instead of having to replace their engines with new quieterengines or disposing of the aircraft all together since it violates thenoise regulations, which constitutes a major financial loss to theowner.

The UHES Ejector design concept is based on SAE Aerospace InformationReport AIR-1191 and method of calculation of the primary exhaust gasflow and secondary cold flow drawn from ambient air. Ejectors are usedextensively in various aerospace applications for providing cooling airto various compartments in engines and aircraft systems. Ejectors, alsoreferred to also as eductors, principle of operation relies on the highspeed engine exhaust gases exiting the engine exit nozzle, withrelatively lower static pressure than ambient surrounding air, enteringa mixing duct entraining with it the ambient air which is at a higherstatic pressure which rushes towards the area of lower static pressure,thereby causing the ambient air to mix with the high speed exhaustgases, thereby reducing the exhaust gas's velocity and noise signaturewhich is caused by the shear forces between static ambient air and thehigh speed exhaust gases, at or near sonic velocity at the exit planefrom the Jet Engine.

Previous designs for ejector hush systems such as U.S. Pat. No.3,820,630 shows an ejector nozzle noise suppressor for a jet engineexhaust is provided by an annular divergent body attached to an exhaustnozzle. The smallest diameter of the divergent body is larger than thediameter of the exhaust nozzle exit to form an annular step whichproduces a shock wave in the exhaust as it passes the step. An annularshroud is disposed around the divergent body and causes outside air topass through voids in the divergent body to mix with the jet exhaustgas. The divergent body includes a plurality of channels with separatorsbetween the channels.

U.S. Pat. No. 7,111,448 describes a jet nozzle mixer includesidentically formed lobes mounted inside the original tailpipeinstallation to provide mixing. The mixer works to mix the engineinternal bypass flow with the internal jet engine core flow to level thedisparate flow velocities, to reduce the peak velocities from the jetengine core and increase the lower bypass velocities of the engineinternal bypass flow, and thereby reduce noise. No external air isinducted into the mixing tailpipe. The internal lobe contours act aslifting flutes, causing mixing of the primary hot and cold flows to mixbefore exiting the nozzle. External lobe contours at the engine exitplane act as venturi chutes, accelerating the cooler ambient secondaryair flow. The external lobes thus act collectively as an injector toforce the cooler ambient secondary flow into the previously mixedprimary flow as it exits the nozzle.

U.S. Pat. No. 3,710,890 describes an exhaust nozzle noise suppressionsystem for turbojet engines based on a centerbody plug mounted to theengine. The exhaust flow from the engine is directed by the centerbodyplug into the ejector airstream from ambient air. A duct shrouds theeductor system which is mounted to the centerbody plug using struts.

In combination, each of the components of the hush kit described hereinreduces noise generated by the jet engine for compliance with FederalAviation Administration noise reduction requirements.

SUMMARY OF THE INVENTION

The subject disclosure presents an innovative patent for an aircraftsystem exhaust system adapting THE ULTRA and/or SQUARE THRUST REVERSERSYSTEM, U.S. Pat. Nos. 5,615,834 and 7,043,897 features to aReverser/Eductor system mounted to the engine, to reduce the jet enginenoise to acceptable noise limits to meet current airworthiness noiseregulations for older aircrafts powered by turbojet and low bypass jetengines.

It is a primary object of this invention to provide a method of reducingjet engine noise at all frequencies with minimal loss of thrust, andpossibly some gain in thrust, by employing an ejector assembly having amixing zone into which a secondary air stream is injected at arelatively higher static pressure.

It is a further object of this invention to provide an ejector assemblyand method wherein the velocity of secondary stream injected into themixing zone of the ejector for mixing with the primary combustionexhaust gas stream from the jet engine is sufficiently high to result inrapid mixing of the primary and secondary gas and air streams in themixing zone and reaches a choked condition at the exit end mixing zonein the duct.

The ejector assembly for the convergent double walled ductconfiguration; can be provided with a means for adjusting the area ofthe mixing section to match jet engine operating conditions.

The forward end of the eductor duct is mounted to the engine turbineflange through mounting struts connecting the eductor double walled ductto the engine exit turbine flange through a nozzle/ring. While at theaft end of the eductor is mounted an ULTRA or SQUARE ULTRA THRUSTREVERSER. The ULTRA or SQUARE ULTRA REVERSER, referred to collectivelyin the text as THE ULTRA REVERSER, consists primarily of an upper andlower clamshell doors mounted on top of the eductor duct exterior skin.

The clamshell doors are either semi-circular orsquare/rectangular/trapezoidal shape similar in concept to theaforementioned ULTRA REVERSER U.S. Pat. Nos. 5,615.834 and/or 7,043,897.The clamshell doors consist of an inner and outer skins mechanicallyconnected at the edges. Two major innovative improvements are made tothe doors. The First improvement to the design of the clamshell doorswhere the inner skin is fitted with guide vanes to direct the cooleductor air towards the middle of the door to blanket the inner skinwith the cool air and to mix this cool air with the hot gases from theengine exhaust to reduce the overall gas temperature to enable the useof lower temperature material in the design of the clamshell doors. TheSecond improvement to the inner skin is by making a slot upstream of theinner skin to allow the reversed flow flowing along the door in thereverse thrust deploy mode to split into two flow components, oneflowing towards the kicker plate then forward to produce the desiredreverse thrust, while the second component of the split flow of thereversed flow flows between the inner and outer skin exiting throughslots in the kicker plate of the inner skin, forward producing a forwardcomponent pushing the first flow component downward and forward insteadof flowing upward, thereby maximizing reverse thrust efficiency.

The innovative actuator design is an actuator within the actuator, whereone of the actuators is used to deploy and stow the clamshell doorswhile the other smaller inner actuator is used to drive fore and aft themovable ⁻fairing. The two actuators within the actuator, on each side ofthe outer skin of the double walled duct, are housed in adepression/blister one on each side of the eductor exterior wall inbetween the clamshell doors and the external surface of the doublewalled eductor duct to provide a smooth exterior surface with noprotrusions, and are attached to a mounting frame on the eductor duct.The actuators are used to move the clamshell doors aft of the eductorduct exit plane, using pivoted linkages connecting the actuators to thedoors and to drive aft and fore the movable fairing during deploy andstow operations of the ULTRA REVERSER. The deployed doors divert theexhaust gases forward causing reverse thrust action for deceleration onthe ground or during an aborted take-off of the aircraft or simply forbraking during taxiing operation on the ground.

THE ULTRA HUSH EXHAUST SYSTEM (UHES) is invented to retrofit the currentexhaust system on turbojet and low bypass aircrafts' engines to meet theairworthiness noise regulations.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained from thedetailed description of exemplary embodiments set forth below to beconsidered in conjunction with the attached drawings, in which:

FIG. 1, 2 and 3 represent respectively a cutaway of the engine and theUHES shown mounted to the aft turbine frame with the ULTRA REVERSER inthe stow position, an isometric view of the UHES with the ULTRA REVERSERin the deploy position and a forward looking aft view of the UHES withthe ULTRA REVERSER clamshell doors deployed.

FIG. 4, 5 and 6 represent respectively a half-section of the UHESshowing the perforated inner skin, the attachment nozzle/ring to theengine turbine frame, the honeycomb lining between the perforated innerskin and the outer skin, the ULTRA REVERSER Upper and Lower Doorshalves. The Struts and frames and the fixed fairing in the stowposition, a cross-section A-A in the blister area showing the perforatedinner skin which is prior art, the sound attenuation honeycomb materialand the outer skin, and an isometric cutaway of the hydraulic actuatorin actuator design.

FIG. 7, 8 and 9 show respectively a cross-section of theactuator-in-actuator design, the ULTRA REVERSER operating linkageskinematics in stow position and the operating linkages in the deployposition which are also prior arts.

FIG. 10 shows a cross-section of an alternate configuration convergentUHES instead of the constant area duct configuration, with a conicmovable device in its center which can be used to control the exit areato optimize the Turbine Engine performance.

FIG. 11 shows a cross-section of the split flow doors in the reversethrust deploy position showing the reverse flow arrows flowing along theinner skin and splitting into two flows, one flowing towards the kickerplate while the other flows between the inner and outer skin exitingthrough slots in the kicker plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The design concept included in preferred embodiments in FIG. 1 is for asound attenuation system referred to as the UHES which is mounted to therearmost aft turbine frame of a Jet Engine 1. The UHES consists of anintegrally constructed double walled duct illustrated in FIG. 1 with aconstant cross-section area or can be a convergent duct as shown in FIG.10. The UHES duct consists of an inner skin 2 integrally constructedwith circular corrugations 3, referred to also as ribs or hats orridges, which act as supporting frames, with the areas in between thoseframes in the inner skin are perforated where sound attenuation material4, which can be honeycomb or any other appropriate material are locatedon top of the perforations 5. The outer skin 6 is continuous with noperforations, and is appropriately fastened or welded to the ribs 3 ofthe inner skin 2.

At the rear end of the integrally constructed double walled duct, twosemi-circular or square shaped clamshell doors 7 are located on top ofthe duct which are stowed during forward flight on top of the duct anddeployed, as shown in FIG. 2, on the ground behind the duct to divertthe engine exhaust flow and eductor air flow forward to decelerate theaircraft. The clamshell doors 7 are operated by two actuators 8 locatedon each side of the duct in an internal depression 9, which drive four(4) mechanical linkages 10 as shown in FIGS. 8 and 9, assuming theactuators are hydraulic for the sake of discussion but the working fluidcan be any appropriate fluid or gas available on the aircraft. Behindeach clamshell door 7, there is a fixed fairing 11, and forward of thedoor there can be a fixed fairing 12 also to stream line the air flowover the double walled duct. On each side of duct the clamshell doors 7,there are two (2) Movable Fairings 13, connected to the actuators 8, oneeach side of the duct, which move aft during deployment of the thrustreverser on the ground. The movable fairings 13 along with the clamshelldoors 7 do contain the exhaust flow from the engine and the eductorduring reverse thrust mode, to prevent any leakage of the exhaust gasesresulting in impingement of the exhaust gases on the fuselage of theaircraft and reduction of reverse flow efficiency.

At the front end of the integrally constructed double walled duct, thereis a nozzle/ring 14 which is mounted to the engine turbine frame of thecore exhaust flow through bolts in flanges or any other appropriateattachment method.

The nozzle/ring can be manufactured using the same approach of theeductor duct, in two walls where the inner one is perforated and theouter is solid enclosing honeycomb or any appropriate sound attenuationmaterial. The nozzle/ring can also be constructed with perforations atthe exit plane to allow the cooler air to flow through and mix with theexhaust gases The exit plane of the ring 14 can be fitted with any ofthe methods used to mix the core engine hot gases with the cooler gasesfrom the low by-pass fan or the eductor ambient air such as a mixer,chevrons or flutes which are currently common in the industry (notshown) to improve noise attenuation of the hot exhaust gases with thecool eductor ambient air. The nozzle/ring 14; supports the double walledacoustically treated duct through four (4) struts 15, in theillustrations for depiction. The struts 15; can have internal passagesto allow some hot exhaust gases to flow through to keep them warm toprevent ice accumulation during flight in icing conditions. Four (4)hinged inlet doors 16 are mounted to the front end of the double walledduct which are open during Take-off and Approach flying modes to allowambient air to be sucked in by the eductor action into the acousticallytreated duct, to mix with the higher speed hot engine exhaust gases, toreduce their noise due to the shear action between the higher velocityexhaust gases and the lower velocity ambient air. The double walledacoustically treated eductor duct will hush the engine noise. The inletdoors 16 can be also fitted with an opening 17 to allow cool ambient airto flow through along the inner wall 2 of the integrally constructedacoustically treated double wall duct to keep it cool and protected fromthe hot engine exhaust gases when the hinged inlet doors 16 are closedduring cruise to reduce ram drag and to streamline the airflow along thesurface of the engine and double walled duct.

The thrust reverser doors inner skin 7A, are fitted with guide vanes 18,which are used to direct the cooler ambient air or low by-pass coolerair from the engine to mix with the hot engine exhaust gas to cool thethrust reverser inner skin 7A during thrust reverser operation mode onthe ground. This can also allow the use of material with lower meltingtemperature such as Aluminum instead of other heavier materials withhigher melting temperature such as Nickel based alloys or Steel.

The thrust reverser inner skin 7A is modified where the inner skin has aslot 38 upstream of the inner skin to allow the reversed flow flowingalong the door in the reverse thrust deploy mode to split into two flowcomponents, the first flow flowing towards the kicker plate 37 thenforward to produce the desired reverse thrust, while the second flowcomponent of the split flow of the reversed flow, flows between theinner and outer skin through slot 38 exiting through slots 39 in thekicker plate of the inner skin which can be fitted with guide vanes 40,directing the split flow forward producing a forward component pushingthe first flow component downward and forward instead of flowing upward,thereby maximizing reverse thrust efficiency.

The thrust reverser doors 7 are operated by Six (6) links 10 on eachside of the thrust reverser doors, where the links pivot around pivotingpoints 19 on the outer skin 6 of the acoustically treated duct. Theforward links 10 are pivoted and are driven by the actuator 8 as shownin FIGS. 8 and 9 which show the stow and deploy positions of the thrustreverser doors during forward flight and reverse thrust mode on theground.

The ACTUATOR-IN-ACTUATOR (AIA) design 8 consists of two concentriccylinders as shown in the cross-section views in FIGS. 6 and 7. Theouter cylinder has two ports 21 and 21A for the hydraulic fluid entryand return to the hydraulic system during the thrust reverser operation.Two lugs 22 attached to the outer cylinder 21, which in turn areconnected to the forward links 10, of the upper and lower thrustreverser doors 7. The outer cylinder is fitted with a pin 23, or morepins if required by design, which fits inside a groove 24 in the outerwall of the inner cylinder 25 to prevent rotation of the outer cylinder.The inner cylinder 25 houses a piston 26 which is connected to themovable fairing 13 through Rod 29A. At both ends of the inner cylinder25, there are two (2) rings 27 which support the outer cylinder 21. Thetwo circular covers at both ends of the inner cylinder 25, have orifices28 to allow the hydraulic fluid, to enter and exit the inner cylinder 25during thrust reverser operation. A rod 29 is concentric to the actuatorand is an integral part of the forward circular cover 27 of the innercylinder 25, which passes through some sealing in the cover 31 of theouter cylinder 20 to prevent the hydraulic fluid from leaking. The rod29 of each actuator 8, is bolted to one of the duct frames 3 and thelongitudinal beam 30, on both sides of the acoustically treated duct.Rod 29A which is connected to the piston 26 is bolted to the movablefairing 13 and also goes through some sealing in the cover 31A toprevent leakage of the hydraulic fluid.

During the thrust reverser deployment operation on the ground, thehydraulic fluid under pressure enters through orifice 21 to fill theforward chamber of the hydraulic actuator 8, exerting hydraulic pressurepushing against the cover 31 of the outer cylinder 20 causing it to moveforward under pressure along the rod 29 and cover 31A will move alongRod 29A. The hydraulic fluid flows also through orifices 28 into theinner cylinder 25 exerting hydraulic pressure against the piston 26which is connected the movable fairing 13 through Rod 29A causing themovable fairing 13 to move aft to close the gap between the thrustreverser clamshell doors and the duct to assure that alt reverse flowgases are enclosed and not leaking laterally impinging on the aircraftfuselage, but directed forward to cause the desired aircraftdeceleration. The movement forward of the outer cylinder 20 causes thelugs 22 which are connected to the links 10, to move forward as wellcausing the links 10 to deploy the thrust reverser doors as shown inFIG. 8. The hydraulic fluid in the back side of piston 26A will beforced into the aft chamber of the actuator 8, which in turn due to theforward motion of the outer cylinder 20 and the ensuing decrease involume of the aft chamber, will force the hydraulic fluid to flowthrough orifice 21A into the return line of the hydraulic system of theaircraft.

During the thrust reverser stow operation, the reverse operation willoccur, the hydraulic fluid under pressure will enter through orifice 21Afilling the aft chamber of the hydraulic actuator 8, exerting hydraulicpressure pushing against the cover MA of the outer cylinder 20 causingit to move aft along the rod 29A and cover 31 will move along Rod 29.The hydraulic fluid flows also through orifices 28 in the inner cylinder25 exerting hydraulic pressure against the piston back face 26A which isconnected the movable fairing 13 causing the movable fairing 13 to moveforward to rest against the thrust reverser doors 7 in the forwardthrust position as shown in FIG. 3. The movement aft of the outercylinder 20 causes the lugs 22 which are connected to the links 10, tomove aft as well, causing the links 10 to stow the thrust reverser doorsas shown in FIG. 8. The hydraulic fluid in the back side of piston 26will be forced into the forward chamber of the actuator 8, which in turndue to the aft motion of the outer cylinder 20 and the ensuing decreasein volume of the forward chamber, will force the hydraulic fluid to flowthrough orifice 21 into the return line of the hydraulic system of theaircraft.

Pin 23 moves inside the groove 24 to prevent any twisting relativemotion between the outer cylinder 20 and inner cylinder 25, therebyassuring proper operation in the linear direction without any rotationof the outer cylinder 20 around the fixed inner cylinder 25, therebyassuring that the actuator is not subjecting the thrust reverserlinkages 10 and pivoting point 19 and duct components to any additionalstresses.

In the convergent MIES duct configuration shown in FIG. 10, a conic body31 made up of two cones, can be mounted to an actuator cylinder 32,assuming hydraulic working fluid but it can use any other type ofworking fluid, which is mounted to one or multiple diametric supports33. A hydraulic line 34 mounted inside the hollow support 33, brings thehydraulic fluid under pressure, inside the cylinder 32, exerting a forceon the piston 35 which is attached to a tension spring 36, forcing thecone 31 to move aft, thereby reducing the size of the exit area tooptimize the engine performance during cruise condition. When theaircraft hydraulic return valve (airframe part not shown) is open, thehydraulic fluid is drained into the aircraft hydraulic system, therebyreducing the force on the piston 35, enabling the tension spring 36 topull the piston 35 forward pulling with it the cone 31, to increase theexit area for the exhaust gases to exit the aft section of theconvergent UHES duct.

The forward cone can be designed as a solid cone or as a double walledcone with acoustic attenuation material sandwiched between the innerwall and the outer perforated wall to contribute to the overall enginenoise reduction.

The foregoing disclosure and description of the invention areillustrative and explanatory thereof; and various changes in the size,shape and materials, as well as in the details of the illustrated systemmay be made without departing from the spirit of the invention.

What is claimed is:
 1. A Jet Engine Noise Attenuation system whichconsist of a double walled duct, of constant area all the way through orconvergent, where the outer wall is solid while the inner wall isperforated sandwiching between them noise attenuation material like whatis referred to in the industry as honeycomb, or any other appropriatenoise reduction and attenuation material.
 2. The double walled duct ismounted to a nozzle/ring using struts at the forward end, forming anassembly which is bolted to the Jet Engine aft turbine frame.
 3. InletDoors are installed at the front end of the nozzle/ring/double walledduct assembly, which can be opened or closed for the operation of theULTRA HUSH ENGINE SYSTEM (UHES) on the ground and during flight. 4.ULTRA THRUST REVERSER new design split flow clamshell doors and movablefairings are installed at the aft end of the nozzle/ring/double walledduct/inlet doors assembly, to be used on the ground to decelerate theaircraft fitted with the UHES.
 5. An ACTUATOR-IN-ACTUATOR (AIA) designoperates The ULTRA THRUST REVERSER clamshell doors and movable fairingsusing mechanical linkages, thereby eliminating the need for additionalactuators to operate the movable fairings.